1. Field of the Invention
The invention relates generally to communications technology, and more particularly to techniques for placing telephone calls over the internet.
2. Description of Related Art
Various techniques have been developed for the purpose of carrying telephonic communications over the internet. Some of these techniques require the use of an internet voice communications software package and voice processing hardware, both of which are typically installed on the user""s personal computer. In response to commands issued by the user, the voice communications software package establishes a communications link on the internet with a remote personal computer selected by the user, as described above. The voice communications software package then controls the voice processing hardware to provide a bidirectional voice communications link between the user and the remote personal computer. Voice processing hardware is available in the form of a voice card which is inserted into an expansion slot of an existing personal computer.
Other types of internet telephony systems, including those presently available from VocalTech/Dialogic, as well as from Vienna Systems, employ gateway devices implemented using personal computers (PCs). The gateway devices use static routing tables which map each of a plurality of respective conventional PSTN telephone numbers to corresponding IP (internet protocol) addresses. Routing table entries must be added and/or removed manually by the user. The gateway utilized in the VocalTech/Dialogic system requires the user to dial out to a special PBX extension corresponding to a local gateway. After calling that PBX extension, the user waits for dial tone, presses the xe2x80x9c*xe2x80x9d key, and dials the code for the destination PBX, followed by the destination extension telephone number. One disadvantage of this scheme is that the user must know ahead of time that the equipment at the destination telephone number includes a gateway for interfacing a PBX to the internet. Additionally, the user is required to know the special telephone number for reaching this PBX.
Improved methods are disclosed for providing a voice communications path over the internet. According to a first embodiment, a first PBX coupled to a first internet gateway device determines whether or not a second PBX has access to a second internet gateway device and, if so, the second PBX sends the IP (internet protocol) address of the second internet gateway device to the first PBX, and the first PBX sends the IP address of the first internet gateway device to the second PBX, over the PSTN (public switched telephone network) and/or over a network signalling channel. The first and second internet gateway devices then set up a voice communications path over the internet between the first and second PBXes.
A further embodiment is for use with a system that includes a first PBX coupled to a first internet gateway device and to a first POTS telephone. The first PBX is equipped to establish a communications path with a second PBX over the PSTN (public switched telephone network), and/or over a network signaling channel. The second PBX is coupled to the second POTS telephone. The method commences when, in response to a telephone number entered into the first POTS telephone and corresponding to a second PBX, the first PBX establishes a signalling path to the second PBX. The first PBX constructs a request packet which includes the IP (internet protocol) address of the first PBX, the IP address of the first internet gateway device, and the telephone number dialed into the first POTS telephone. The first PBX sends the request packet to the second PBX over the PSTN, and/or over the network signaling channel. In response to the receipt of the request packet, the second PBX checks to determine whether or not it is coupled to a second internet gateway. If so, the second PBX constructs a response packet including the IP address of the second gateway, and sends the response packet to the first PBX over the PSTN, and/or over the network signaling channel. Upon receipt of the response packet, the first PBX sends a reservation signal to the first gateway device and, in response to the reservation signal, the first gateway device requests the internet to provide two internet channels between the first gateway and the second gateway. These internet channels provide a voice communications path between the first POTS telephone and the second POTS telephone, wherein the path includes the first PBX, the first gateway device, the internet, the second gateway device, and the second PBX.